Largest Earthquakes in the United States

The lists and statistics on this webpage have not been updated since December 2012. Many of these will be updated and available when we have completed the transition into the new earthquake database. We hope to provide this sometime in 2015.

Note: Widely differing magnitudes have been computed for some of these
earthquakes; the values differ according to the methods and data
used. For example, some sources list the magnitude of the 8.7
Rat Islands earthquake as low as 7.7.
Similar variations exist for most events on this
list, although generally not so large as for the example given.

In general, the magnitudes given in the list above have been
determined from the seismic moment, when available. For very large
earthquakes, the moment magnitude is considered to be a more
accurate determination than the traditional amplitude magnitude
computation procedures. Note that all of these values can be
called "magnitudes on the Richter scale," regardless of the method
used to compute them.

Revisions
The Andreanof Islands, Alaska earthquake of 1957 03 09, previously listed with a magnitude of 9.1,
has had its magnitude reviewed, and it was updated to 8.6.